Relay



W. D. HAILES EIAL,

RELAY iFiled Feb. 18. 1942 2 Sheets-Sheet 1 INVENTOR5 WDHm'les and WMBarker W BY 7%! THEIR ATTOR N EY April 18, 1944. w, g g HAL 2,346,751 RELAYFiled Feb. 18, 1 942 2 51.1691353 51166 1, 2

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v v. y y a v P I 4 *PM 5 2 ///A[ f PM+4 EM 34/ v 1 3 rF 9/ i IIINVENTORS VgeHailes and W.M.Ba.rker

O A'ramaturc travelfrom neutm! CHARACTERISTIC PULL E LOAD CURVES THEIRATTORNEY Patented Apr. 18, 1944 I RELAY William D. Hailes, Brighton, andWilliam M. Barker, Greece, N. Y., assignors to General Railway SignalCompany, Rochester, N. Y.

Application February 18, 1942, Serial No. 431,334

9 Claims.

This invention relates in general to electromagnetic relay and ha moreparticular reference to such a relay of either the two-position orthree-position polar type and one particularly adapted for use as a linerelay in centralized trafiic control systems and the like.

One purpose of the present invention is to provide a relay which is veryrugged, is most dependable in its operation, and still is very eflicientin energy consumption.

A further object of the invention is to provide novel and improvedadjusting means for varying the mechanical load characteristics of therelay so as to accurately fit the magnetic pull characteristics of therelay.

A further object of the invention is to provide a relay which hassubstantially constant operating characteristics regardless of whetherit be housed in cabinets made of magnetic or nonmagnetic materials, andalso to a limited extent irrespective of external magnetic fields.

Further objects, purposes and characteristic features of the inventionwill appear as the description thereof progresses, reference being madeto the accompanying drawings, showing solely by way of example and in noway whatsoever in a limiting sense, one form which the invention canassume. In the drawings:

Fig. 1 is an isometrical view of one embodiment of this invention.

Fig. 2 is a plan view of the embodiment with parts broken away.

Fig. 3 is a sectional view on line 33 of Fig. 2, as viewed in thedirection of the arrows.

Fig. 4 is a diagrammatic view of a control system employing relaysconstructed in accordance with this invention.

Fig. 5 is a graph illustrating the operating characteristics of relaysconstructed in accordance with this invention.

The relay, as referred to above, is of the polar three-position typewith means for biasing it to its neutral position, or of the polartwo-position type with means for biasing it to one extreme position. Asreadily appears from Figs. 1 and 2 of the drawings, the relay is mountedon a base B, made of steel or other magnetic material, for a purpose tobe described below.

The relay proper is supported on the base by non-magnetic supports S,three in number, which supports are made of brass or other non-magneticmaterial. The core and coil structure C is carried in a frame whichincludes a front plate FP, which is L-shaped in form and extends the endby screws or the like i, to a back strap BS of magnetic material towhich the two cores l! are connected in a manner not shown. This frontplate is made of non-magnetic material such as brass. Carried at therear of the front plate is a contact carrying plate CP of non-magneticmaterial, to which is attached a block 2 of insulating material, holdingvarious contact fingers as 3, 4, 5 and 6. At the front end of the frontplate is a top plate I? of non-magnetic material, which aids insupporting a pivoted armature 1 which is pivoted at 8 and 9, on the topplate TP, and on a lug ill of the front plate FP, respectively.

Extending beneath the core and coil structure is a permanent magnet PMwhich at its rear end is connected to the back strap BS or magneticmaterial which in turn magnetically connects the rear end of the twocores H together., This permanent magnet PM at its front end terminatesvery closely adjacent the central portion of the armature. Thispermanent magnet produces magnetic fields through the two air-gapsbetween the two ends of the armature I and the front ends of the twocores ll of substantially equal intensity when the armature is in theneutral position and with the coils C deenergized.

The contact fingers 4 and 6 are operatively connected to the armature bymeans of an operator l2 extending toward the rear of the relay from itsarmature I and having an upstanding triangular finger 13 which operatescontact finger 6 toward contact 5 and in turn through the medium of apusher I 4 moves the contact finger l toward the contact finger 3 so asto close circuits in the usual manner.

Although unnecessary for this disclosure, to show them in detail, to theright side of the relay as viewed in Fig. 2 are other contact fingersi5, etc.

The contact fingers project from the holding block 2 of insulatingmaterial and are connected to wires which can be conveniently formedinto a cable l6 which passes beneath the relay and to the front thereofto be connected to the socket members I6 of a detachable plug connectormember ll, fastened to base B as at [8. In this manner the entire relayand base, as Well as its connecting wires, can be quickly connected to01' disconnected from a supporting panel or other supporting means. Theopening I9 in the base is to accommodate additional plug connector meansif needed.

Depending from the rearwardly extending length of the relay to beconnected at its rear operating member l2 which is fixed to and moveswith the armature, is a, pin 25 the sides of which are engaged bybiasing spring fingers 22 and 23 which springs are carried by what maybe conveniently termed an adjustment plate AP. Ad- .iustment plate APcarries a pin 2| directly beneath, and concentric with, pin 23.

The adjustment plate AP has upturned sides 24 and 25 which "are slottedlongitudinally, as at 26. Slidable in th'ese'slots 26 are blocks '2'!(see Fig. 3) each of which is threaded to receive an adjusting screw 28.Each screw 28 extends inwardly to bear at its inner end as at 29 againstits associated biasing spring and is held in adjusted position by a locknut 30 and an associated washer on the outer side and by the block 21into which it is screwed on the inner side. Thus, by loosening the locknut 39 each screw 28 can be slid to a different position in the slot 26and can be turned into or out of the block 27 to bear with greater orlesser pressure on the biasing spring 22 or 23 which it controls. Thearrangement is "symmetrical on each sideof the relay so as to renderadjustable the spring {nonuseful load) load upon the relay for eachdirection of movement of the armature 1 from its neutral position, toresult in the desired nonuseful load characteristics of the relayregardless of the polarity of the applied current and the correspondingdirection of movement of the armature.

Referring now more particularly to the showing in Fig. 2 and assumingthat the relay is energized with a polarity which causes the operatorfinger iii to move to the left, it can be seen that the movable contactfingers 4 and 6 are moved to make up their front points 3 and 5,respectively. Upon the armature first moving it must move the contactfingers i and '6 against the spring load of these fingers and must alsomove the biasing spring 22. It should be understood that there isinitial or trapped tension in spring 22 by reason of the tension havingbeen trapped by the fixed stop pin 21. Similarly there may be initial ortrapped tension in contact fingers 4 and '6 which was trapped by thefixed stops 6 and 6 respectively. After the contacts 4 and 6 have firstmade up with contacts *3 and the movement continues to thus build upcontact pressure and hence an added'usefu'l load above that of thenon-useful load exerted by springs 22, 4 and '6 which must be carried bythe relay armature and is added at this point (indicated at P in Fig. 5)in the movement of the armature. This added load or useful load is dueto the spring exerted forces of the front contact fingers 3 and 5carrying the front points and is called useful because it constitutescontact pressure.

It should be understood that although contact springs d and 6 may haveinitial or trapped tension no such spring tension is trapped in contactfingers 3 and 5 the stops 3 and 5 being barely in con-tact with springs3 and 5 respectively.

The operating characteristics of the relay can be readily understoodfrom a consideration of the curves shown in Fig. '5. Some of thesecurves show loads and others show various values of pull for differentpositions of the armature in its travel from it's neutral to one of itsoperated positions. On the horizontal axis is represented from left toright the amount of movement of the armature in moving from its biasedneutral position to one of its fully attracted positions, indicated bythe dotted line F, where the residual pin 46 is in contact with the poleiaceof core Ii. This distance in the particular example of one relayadjustment illustrated is measured at the residual pin. On the verticalaxis measured from zero upwardly is indicated, the mechanical load andthe magnetic pull at various positions of the armature.

In moving the armature from its neutral position toward one of the polefaces of the electromagnetic core structure a pull due to theredistribution of the fluxes from the permanent magnet PM develops assoon as it moves from its center position and the pull due to thisredistribution of permanent magnet flux is represented by the curve PM,conveniently called the permanent magnet pull curve. In addition to thismagnetic pull, there is the magnetic pull due to the electro-magnet whenenergized by energizing current of a particular value, and the sum ofthese two pulls is represented by the curve PM +EM, that is, permanentmagnet pull plus electro-magnet pull. This pull due to magnetic forcesPM +E' M and plotted along the vertical axis, as stated above, in orderthat the relay will pick up when energized, must throughout the entirearmature movement be greater than the total non-useful load due to thesprings, such as springs 22, 4 and 6.

The load, due to moving the biasing spring such as spring 22 and due tomoving the contact fingers, such as fingers i and 5, is represented bythe curve NUL, or non-useful load, since it can be convenientlyconsidered that moving this load produces 'nouseful result. This curveNUL extends from point A to point D in Fig. 5. A really useful result isrealized only after the contacts have touched and further movement hasbuilt up contact pressure enough to insure a proper flow of currentthrough the circuits which have been closed by the relay contacts. Thecurve NUL+ UL represents the total load TL and includes not only theabove non-useful load but also the useful load which is encountered inbuilding up contact pressure. From the diagram, it can be seen thatafter a'movement of the armature to point 'P, the contacts close and thefurtheir movement includes building up contact pressure by'flexing thefront contact fingers 3 and 5, and this abruptly changes the slope ofthe total load curve TL as shown by the angle a at P in Fig. .'5. Theuseful load is therefore the difference expressed by curves P to E and P1:01).

It is thus apparent from Fig. 5 that the trapped tension, comprising thesum of the trapped tens'ions of springs 22, d and 6, in the particularexample of relay adjustment illustrated in Fig. '5,

r is shown by curves A to D or NUL, and that the magnetic pull due toapplying said predetermined operating current to the relay andrepresented by curve PM +EM amounts to slightlymore than this trappedtension at zero armature movement. Consequently with this currentapplied movement of the armature in a counter-clockwise directionbegins. As the armature travel increases the nonuseful load builds up instraight line fashion until the armature travel has reached the positionrepresented by point P. At this point P (see Fig. 5) in the armaturetravel the contacts 5-6 and 3-4 close and cause the total load TL tobuild up at a faster rate as shown by the solid line P to E beyond pointP. The useful load (contact pressure) starts at this point P andis addedto the non-useful load NUL. This same rate of build-up (straight line)of the total load continues after point P until the armature 7 strikesthe residual pin 4!! indicated by the dotted line F. It will be seenthat the entire curve of total load TL falls below the curve of totalmagnetic pull PM +EM from which it is seen that the armature is actuatedall the way and against the residual pins upon the application of thiscurrent of particular value. It is also seen that all of the total loadcurve TL is above all of the curve PM EM which is assurance that therelay will drop if the particular current conveniently called pick-upcurrent is reduced to substantially one-half value. This also assumesthat in the meantime the current has been increased way above thepick-up value to a point where saturation of the iron takes place, sothat a certain amount of pull due to residual magnetism is included inthe pull curve PM EM, and that the relay will drop away upon reductionof the current to one-half of the pick-up value in spite of thisresidual.

It is readily understood that when contact wear occurs the point P inthe total load curve will be shifted farther to the right along thedotted line NUL and if continued to an appreciable extent will cause aportion of the total load curve to fall below the half-current magneticpull curve PM EM Under this condition the relay will not drop away ifthe current is reduced to onehalf of its original value but will drop ifthe current is reduced to a somewhat lower value. This latter conclusionis apparent from the fact that with zero contact pressure, in which casethe lines TL and NUL will be coincident and lie along the line NUL, allof the total load curve TL falls above all of the magnetic pull curvedue to the permanent magnet as illustrated by line PM. Therefore eventhough appreciable contact wear takes place the relay will release whenthe current is reduced to a fraction of its minimum pick-up value,whereas if the load curve after appreciable loss of contact follow wereto come lower than the pull curve PM due to the permanent magnet therelay would fail to drop even though all current were removed from therelay coils. In other words, the relay is constructed to allow contactwear until it fails to close its contacts upon being picked up and willstill drop away upon deenergization thereof. The minimum load point ofcurve NUL is determined by the amount of trapped tension exerted bysprings 4, 6 and 22, the portion contributed by spring 22 may be variedby turning the adjusting screw 28. The slope of build-up of the loadcurve up to the point P is determined by the stiifness of springs 4 and6 and also by the stiffness of spring 22 which may be varied by slidingthe adjusting screws 28 in the slots 25. The build-up or slope of theuseful portion of the total load (the portion P to E beyond the point P)may be varied by properly selecting the material and crosssection of thecontact springs 3 and and by changing their bearing point by properlyselecting the length of the stop members 3 and 5 The relay of thepresent invention is thus constructed to cause the total load curve TLof the relay to approximate the curves of magnetic pull for both fullenergization PM +EM and half energization PM ,EM of the electro-magnetthereof and causes it to lie wholly between these two magnetic pullcurves which assures both picking up of the relay at the pick-up valueenergization thereof and dropping away of the relay if the energizingcurrent is reduced to onehali of the pick-up value when the relay is innormal adjustment. This construction assures that the relay armaturewill not begin to pick up until the current is increased to the pick-upvalue when it then moves to the fully picked-up position without furtherincrease in current. Similarly, the relay armature will not begin torelease until the current has been reduced to essentially one-half ofthe pick-up value when it then moves to the fully released positionwithout further reduction in current.

This relay can be employed in any desired capacity but is of particularvalue in centralized traffic control systems such as diagrammaticallyshown in Fig. 4. In such systems, a large number of these relays areconnected in series in a line circuit extending at times for many milesand for the functioning of the system in a proper manner, the opening ofthe line circuit must cause all the relays to release. However, it canbe seen that, if the switch 38 at the end of the line circuit beintermittently opened, as is the case in a coded signalling system, theamount of leakage between the lines of the circuit and the fiow ofcharging current due to the condenser effect produced by these long linecircuits might permit enough current to flow through the relays near thebattery end of the system to hold them up regardless of the intermittentopening of switch 38.

With the above considerations held in mind it can be seen why the relayis so adjusted as represented by curve PM EM that when the energizingcurrent is decreased to anything less than one-half, the minimum pick-upvalue is insufiicicnt to hold the relay up, and hence it will release itshould. It is of course understood that in practice the current appliedto the line circuit is greater than this minimum pick-up value in orderto provide ample operating margin considering leakage currents and thelike.

It can also be seen from. Fig. 5 that the relay. in adjustment, has suchcharacteristics that the load curves, both the non-useful load NUL andthe combined non-useful and useful load curves, constituting the totalload curve TL, both lie above the permanent magnet magnetic pull curvePM. Thus, even though, due to Wear, or accident, or otherwise, thecontact pressure should completely disappear, the relay still could nothold up when deenergized, whereas. if the curve PM should lie in partabove the non-useful load curve NUL the relay would not drop upondeenergization of its winding.

Referring again to Fig. 5 the area below curve PM is the uncontrollableportion of the pull characteristic oi" th relay. The area above curve PMis controllableby the excitation of the relay windings. The relay ofthis invention is constructed so that the load characteristics asrepresented by curves NUL and TL lie wholly within the controllableportion of pull characteristics of the relay.

In order to develop contact pressures of sufficient amounts to guaranteereliable contact operation and in order to develop sufficient nonuseiulload greater than the pull represented by curve PM. it necessary todevelop a total load in the fully picked up position of the relay asshown by curve TL at point E. The point E thus locates one point on thepull curve PM 571! namely, the pull curve of the relay when the windingsare energized at a level at which the relay shall just release. When thearmature begins to more, it highly desirable that it shall move to thefully released position without a further reduction of the current inthe relay coils. To accomplish this. it is necessary to adjust the loadcurve TL that it lies above pull curve PM /2EM at all points. It is alsohighly desirable that when the excitation of the relay is increased tothe pick-up value for which the pull curve PM +EM starts at A, that thearmature shall complete its pick-up movement without further increase incurrent. This means that the load curve TL should lie below theparticular pull curve PM +EM which is required to start the armaturetowards its pick-up position. The point A on the load curve TL musttherefore be at or just below the point A on the pull curve PM +EM It isalso desirable that the relay shall respond to as small a change inexcitation of its windings as is practicable. This means that if theload curve TL is made to approximate the slope and curvature of the pullcurve PM /gEM, it will be unnecessary to employ a large increase inexcitation to cause pick-up of the relay armature and therefore therelay will possess the de sirable high release characteristic. That is,for a given pick-up only a small reduction in energy is required tocause the relay to release. Stated another way the more nearly the loadcharacteristic of the relay is fitted to the pull characteristic of therelay the smaller the amount of increase required to pick the relay upabove the value at which the relay releases.

From the foregoing it can be seen that it is highly desirable to be ableto control the amounts of the various portions of the mechanical load ofthe relay and also the slope at which these mechanical loads increasewith the movement of the relay armature. Stated broadly, it is desirableto be able to control the shape of the load curve TL and to this end therelay of the invention employs the following features namely a choice ofcontact springs of proper width and thickness plus a choice of thelength of pressure members 3 and 5 plus the adjustable means for varyingthe intensity and slope of the centering spring 22.

For example, the choice of contact spring material and proper width andthickness for fingers 3 and 5 plus the choice of pressure members 3 and5E oi the proper length produces the required contact pressurerepresented by the difierence between the pressures and point E on curveTL, and the point- D on curve NUL and also the correct slope withrespect to curve NUL and represented by the angle a, so as to intersectcurve NUL at point P, the point of engagement of the contacts.Similarly, the choice of spring material and the proper width andthickness for fingers 4 and 6 and the choice of spring material and theproper width and thickness for centering spring 22 plus the adjustablefeature provided by the adjusting screw 28 enables adjusting thenon-useable portion of the load characteristic to exert a load as shownat D on curve NUL which is greater than the pull supplied by thepermanent magnet as represented by the point G on curve PM and to fixthe slope of this curve NUL so that the total load curve TL lies abovepull curve at release value, i. e. PM EM, at all points.

The adjusting means for adjusting the load curve of the relay isprovided so a to be enabled to fit this curve properly to the magneticpull curve. By sliding the adjusting screws in the slots the effectivelength of the biasing springs and hence the slope of the load curve canbe changed, the shorter the distance from the adjusting screw to thearmature operated pin 28 the steeper the curve, To vary the initialpoint of the curve, that is, the point at substantially zero armaturemovement, the screw need merely be turned in or out so as to adjust, ineffect, the trapped tension in the biasing spring 22 or 23 involved. Thetrapped tension in the centering springs 22 is exerted against fixed pin2|, and holds the armature in its center, or neutraLposition when therelay is not energized and upon application of current until the currenthas increased to the pick-up value. Upon movement of the armature fromits normal position all of the force of one of the springs 22 or 23' isexerted against the fixed stop pin 2| whereas all of the force of theother spring 23 or 22 is exerted to oppose movement of the armature.

As stated above, the relay is mounted on a base of magnetic materialsuch as steel. This is done to maintain substantially constant operatingcharacteristics regardless of whether the relay be housed in a cabinetmade of magnetic material such as steel, or in a cabinet made ofnonmagnetic material such as Wood, or the like. By placing the relayclose to a relatively large base of magnetic material the relaycharacteristics are stabilized and are not materially varied by beinghoused, for example, in a metal cabinet, or close to other devices ofmagnetic material. This construction ofiers the further advantage thatit maintains substantially constant operating characteristics for therelay of this invention even though it is subjected to the straymagnetic fields set up by a group of relays with which it may be housedin a common cabinet. The magnetic metal base stabilizes the operatingcharacteristics of the relay by providing a relatively low reluctanceshunt or leakage path in parallel with the flux path which carries therelay operating fluxes so that when the relay is brought intojuxtaposition with other magnetic material bodies or within stray fieldsset up by other devices the change in the flux condition in theoperating flux path as a result of external bodies or fields issubstantially negligible.

A relay of this type is of distinct advantage in centralized trafiiccontrol systems as referred to above. It is not merely a matter ofeconomizing in energy that constitutes the problems, since, if thevoltage at the battery end be increased too greatly, the leakage mayincrease to such an extent that if the relays pick up satisfactorilywhen the switch 38 is'closed, they will not release when the switch isopened.

On the other hand, if the battery voltage be decreased too greatly so asto decrease leakage and hence prevent the relays holding up when theswitch is open, the voltage may be too low to pick up relays at theswitch end of the line when the switch is closed. Thus, a very sensitiveand high drop-away relay such as described above is of particular valuein connection with such systems as described above and similar systems.

One variation in the line circuit of these sys tems employs relays withhigh impedance windings connected in multiple between the line wires ofthe system. These relays must drop away when a shunt is momentarilyapplied between the line wires at a relay location. irrespective ofwhether that relay location is near the battery end of the line circuitor near the open end of the line wires. A sensitive relay with a highdrop-away is particularly valuable in this application of the relay ofthis invention. A sensitive relay avoids the necessity of transmittingrelatively large amounts of energy over the line circuit and a reliablehigh drop-away characteristic of the relay insures that the relay willrelease without requiring that the line potential be reduced to a verylow value by the application of the controlling shunt. In other words,the high release characteristic of the relay avoids the need of reducingthe line potential to substantially zero in order to guarantee releaseof the line relay. This is particularly advantageous where the linewires of the system are used jointly for centralized trafiic control andtelephone purposes.

The relay involves protection against lightning in that the first fewturns of the winding at each end are either of larger wire than the restor are of the same wire, but in either case, are more heavily insulatedand are more widely spaced from each other, and from the remainingturns. This provides a choke winding and protects the main body of thewinding by absorbing the voltages induced by lightning within a portionof the winding insulated to withstand these voltages.

As illustrated in Fig. 4, the main winding of a relay of this type isindicated at 3| with the first few turns at each end indicated as 32 and33 spaced farther apart. If lightning surges occur the arresters as 34and 35 will limit the voltages appearing at the relay winding to theorder of the break-down voltage of the arresters which voltage is alsolow enough to be withstood by the insulation employed for the turns 32and 33.

Since lightning surges are characterized by a very steep wave front,that is, are of extremely high frequency, the voltage impressed by thesesurges upon windings is absorbed in a relatively few number of turns andtherefore the voltage gradient is very steep for the first few turns ofthe winding. This means that the inter-turn voltage will be high for thefirst few turns and thus will require additional insulation or spacingor both in order to prevent damage from lighting surges. Therefore, theend turns are provided with extra insulation strength to a sufficientnumber of turns to absorb the maximum voltage, established by thelightning arresters, without damage.

Furthermore, by spacing a few turns on each end of the winding from eachother andfrom other layers of the winding the distributed capacity ofthe end turns is reduced, and aids in distributing the surge voltageamong a suitable number of turns.

Obviously if direct current of one polarity only is applied to the relaythe relay becomes a twoposition relay. Also, special adjustments of therelay may be made if it is to be used as a twoposition relay only.

One of the dimculties encountered in relay construction employingpermanent magnets is to prevent flux set up by the permanent magnet whenthe relay is in its actuated position, and represented by the pull G,from preventing release of the relay upon decreasing of the current acomparatively small amount below the pick-up value. In applicantsconstruction this diificulty has been removed by properly selecting theload of the relay for all points of armature position by selecting thetrapped tension and pressure build-up of the springs 4, 6 and 22 (line Ato P) supplemented by further preselecting of contact pressure build-up(line P to E) determined by spring fingers 3 and 5. Not only does thisfeature cause the load curve TL (P to E to properly fit between the pullcurves PM +EM and PM A EM and thereby greatly improve the efiiciency ofthe relay but it also at the same time affords a large amount of contactpressure (D to E) with a considerable amount of wipe of these contactsand a wide spacing of contacts when the relay is in its non-actuatedposition. In other words, the construction is such that almost everyelement of the current is used to do necessary work, that is, operatethe armature and create contact pressure.

The above rather specific description of one form of the invention hasbeen given solely by way of example and is not intended in any mannerwhatsoever in a limiting sense. it is to be understood that variousmodifications, adaptations and alterations may be applied to meet therequirements of practice Without in any manner departing from the spiritor scope of the inven tion except as limited by the appended claims.

Having described our invention, we now claim:

1. In relays, in combination; a magnetic structure including a core, acoil on said core, a movably mounted armature and a permanent magnet soassociated with said core and armature that the application of currentto said coil causes magnetism from said permanent magnet to beredistributed in the working air gap between said core and saidarmature; two coaxial members of like diameter one fixedly supportedwith respect to said core and the other operatively connected to saidarmature in such manner as to cause said other member to move withrespect to said one member so that their axes remain in parallelrelation to each other but separate from each other as said armaturemoves from its normal position; two springs arranged on opposite sidesof said coaxial members having one end fixed and having the other endengage both of said members; means to adjustably change both or eitherthe effective lever arm of said springs and the initial force exertedthereby on opposite sides of said coaxial members when said armatureassumes its normal position.

2. In relays, in combination; a magnetic structure including two cores,a coil on each core, a movably mounted armature and a permanent magnetso associated with said core and armature that the application ofcurrent to said coil causes magnetism from said permanent magnet to beredistributed in the working air gap between said cores and saidarmature; two coaxial members of like diameter one fixedly supportedwith respect to said core and the other operatively connected to saidarmature in such manner as to cause said other member to move withrespect to said one member so that their axes remain in parallelrelation to each other but separate from each other as said armaturemoves from its normal position; a spring arranged on one side of saidcoaxial members having one end fixed and having the other end engageboth of said members; means to adjustably change both or either theefiective lever arm of said spring and the initial force exerted therebyon the sides of said coaxial members when said armature assumes itsnormal position.

3. In relays, in combination; a magnetic structure including a core, acoil on said core, a movably mounted armature and a permanent magnet soassociated with said Core and armature that the application of currentto said coil causes magnetism from said permanent magnet to beredistributed in the working air gap between said core and saidarmature; two coaxial members of like diameter one fixedly supportedwith respect to said core and the other operatively connected to saidarmature in such manner as to cause said other member to move withrespect to said one 'memberjsothat their axes remain in parallelrelation to each other but separate from each other as said armaturemoves from its normal position;

a spring arranged on one side of said coaxial members having one endfixed and having the other end engage both of said members; means toadjustably change both or either the efiective lever arm of said springand the initial force exerted thereby on the sides of said coaxialmembers when said armature assumes its normal positionra front springcontact finger fixed at one end and having a stop touching it withoutinitially tensioning it, so as to substantially prevent its movement inone direction only; and a movable spring contact finger operativelyconnected to and movable with, said armature, in a direction opposite tosaid one direction and into contact with said front spring contactfinger, the movable finger having a stop member and being initiallytensioned against itsstop member to bias said movable spring fingerawayfrom said front spring contact finger, whereby said spring contactfingers are prevented by said stops from making unauthorized contact andthese contact fingers do not impose additional trapped tension abovethat imposed by said spring and the movable contact fingers when contactis made during actuation of the relay from its normal position.

l. In relays, in combination; a magnetic structure including two cores,a coil on each core, a movably mounted armature and a permanent magnetso associated with said cores and armature that the application ofcurrent to said coils causes magnetism from said permanent magnet to beredistributed in the working air gap between said cores and saidarmature; two coaxial members of like diameter one fixedly supportedwith respect to said cores and the other operatively connected to saidarmature in such manner as to cause said other member to move withrespect to said one member so that their axes remain in parallelrelation to each other but separate from each other as said armaturemoves from its normal position; two springs arranged on opposite sidesof said coaxial members having one end fixed and having the other endengage both of said members; meansto adjustably change both or eitherthe eifective lever arm of said springs and the initial force exertedthereby on opposite sides of said coaxial members when said armatureassumes its normal position; a front contact, a movable contact operableby said armature and exerting trapped tension when moved to engage thefront contact; the front contact not exerting trapped tension whenengaged by the movable contact, whereby the load curve imposed by saidsprings, said movable contact and said front contact starts at a pointabove zero and builds up at two different rates without an interveningoff-set.

5. In relays, in combination; a magnetic structure including a core, acoil on said core, a movably mounted armature and a permanent magnet soassociated with said core and armature that the application of currentto said coil causes magnetism from said permanent magnet to beredistributed in the working air gap between said core and said armaturein. two different ways depending on the polarity of the applied current;two coaxial members of like diameter one fixedly supported with respectto said core and the other operatively connected to said armature insuch manner as to cause said other member to move with respect to saidone member so that their axes remain in parallel relation to each otherbut separate from each other as said armature moves from its normalposition; springs arranged on opposite sides of said coaxial membershaving one end fixed and having the other end engage both of saidmembers; and means to adjustably change both or either the effectivelever arm of said springs and they initial force exerted thereby on thesides of said coaxial members with said armature assuming its normalposition.

6. In relays, in combination; a magnetic structure including two cores,a coil on each core, a movably mounted armature and a permanent magnetso associated with said cores and armature that the application ofcurrent to said coils causes magnetism from said permanent magnet to beredistributed in the working air gaps between said cores and saidarmature in two different ways depending on the polarity of the currentapplied to said coils; two coaxial members of like diameter one fixedlysupported with respect to said core and the other operatively connectedto armature in such manner as to cause said other member to move withrespect to said one member so that their axes remain in parallelrelation to each other but separate from each other as said armaturemoves from its normal position; springs arranged on opposite sides ofsaid coaxial members having one end fixed and having the other endengage both of said members; means to adjustably change both or eitherthe effective lever arm of said springs and the initial force exertedthereby on the sides of said coaxial members when said armature assumesits normal position; front spring contact fingers each having a stopmember touching, but not biasing, it, so as to substantially prevent itsmovement in one clirection; and movable spring contact fingers eachoperatively connected to said armature and movable -in a directionopposite to said one direction and into contacting relationship withsaid front spring contact fingers and each having a stop member toprevent it from moving when said armature is. moved in an oppositedirection, whereby said front spring contact fingers are prevented bytheir associated stops from making unauthorized contact and do notimpose additional trappedtension above that imposed by said springs andmovable fingers when contact is made between said movable springcontacts and said front spring contacts during actuation of the armaturefrom its normal position.

'7 In a relay structure, the combination with a pair of cores connectedby a back yoke, coils on said cores to magnetize the free ends of saidcores so as to have magnetic poles of opposite olarity,

an armature pivoted near the middle and having opposite ends in closeproximity to the free ends of said cores, a permanent magnet forcreating magnetic fields in multiple through said cores and passingthrough said armature, two members of substantially the same diameterone fixedly supported relatively to said cores and the other operativelyconnected with said armature and arranged coaxially when said armatureassumes its normal non-actuated position and having their axes parallelbut separated from each other when said armature assumes an actuatedposition, two fiat springs having one end fixedly supported with respectto said cores and having their free ends bearing against. opposite sidesof both of said members when said armature is in its non-actuatedposition, a bias adjuster screw for each of said fiat springs, means formounting each adjuster screw in contacting relation with its fiatspring, means for adjustably changing the contacting relationship ofeach adjusting screw both transversely and longitudinally with respectto its associated flat spring, whereby to respectively adjust theinitial trapped tension and the rate of pressure build-up of the forceexerted by such spring upon said movable member as said armature ismoved from its normal position.

8. In a relay structure, the combination with a pair of cores connectedby a back yoke, coils on said cores to magnetize the free ends of saidcores so as to have magnetic poles of opposite polarity, an armaturepivoted near the middle and having opposite ends in close proximity tothe free ends of said cores, a permanent magnet for creating magneticfields in multiple through said cores and passing through said armature,two members of substantially the same diameter one fixedly supportedrelatively to said cores and the other operatively connected with saidarmature and arranged coaxially when said armature assumes its normalnon-actuated position and having their axes parallel but separated fromeach other when said armature assumes an actuated position, two flatsprings having one end fixedly supported with respect to said cores andhaving their free ends bearing against opposite sides of both of saidmembers when said armature assumes its nonactuated position, a biasadjuster screw for each of said flat springs, means for mounting eachadjuster screw in contacting relation with its fiat spring, means foradjustably changing the contacting relationship of each adjuster screwboth transversely and longitudinally with respect to its associated fiatspring, whereby to respectively adjust the initial trapped tension andthe rate of pressure build-up of the force exerted by such spring uponsaid movable member as said armature is moved from its normal position,spring contacts, other contacts operable by said armature and engageablewith the spring contacts,

pressure members, said spring contacts bearing against the pressuremembers, the pressure members being of such a length as to produce theproper build-up of contact pressure from the point at which the springcontacts are engaged by the other contacts to where the armature hasbeen operated to its fully acuated position.

9. In a relay, a core and coil structure, a permanent magnet, and anarmature magnetically associated with said permanent magnet and saidcore and coil structure, biasing means for urging said armature to aneutral position by trapped tension and producing a predeterminedbuild-up when moved from such neutral position, and including, movablecontact spring fingers moved upon initial movement of the armature, anda spring having trapped tension imposed against a stop when saidarmature is in its neutral position, the tension of said spring buildingup at a predetermined straight line rate upon movement or" said armaturefrom its neutral position, and other contact spring fingers engaged bysaid movable spring fingers to cause additional build-up of the load inaddition to that imposed by said biasing means, whereby the load curvestarts at an appreciable value upon initial movement of the armature,then builds up at one predetermined rate followed by a higher rate; saidcore, coil and permanent magnet structure being of a construction suchthat the torque curves due to energization of said coil with a currentof a predetermined value and with current of one-half that value,respectively conform in shape to said load curve and fall respectivelywholly above and wholly below said load curve, whereby said relay willpick up if energized by current of said one predetermined value, andwill drop if the current be reduced to one half of that value.

WILLIAM D. HAILES. WILLIAM M. BARKER.

